1. Field of the Invention
The present invention relates to a clutch, and particularly to an improvement in a clutch comprising: a bottomed cylindrical clutch housing made of a light alloy and having an end wall; a retainer plate secured to the end wall with a given distance left therebetween; an iron transmitting gear disposed between and connected to the end wall and the retainer plate, for rotation relative to the end wall and the retainer plate in a predetermined range of angle; damper springs interposed between the transmitting gear and the clutch housing as well as the retainer plate, for moderating a torque shock generated between them; belleville springs interposed between the transmitting gear and the clutch housing as well as the retainer plate, for urging the transmitting gear toward one of the clutch housing and the retainer plate; and a thrust washer mounted to an outer face of the end wall of the clutch housing, for preventing contact between the end wall and the belleville springs as well as the transmitting gear.
2. Description of the Related Art
In a conventional clutch, belleville springs provide a moderate resistance to the rotational friction between a clutch housing and a transmitting gear, to thereby contribute to inhibition of the vibration of damper springs. Also, a thrust washer avoids wear of the clutch housing made of a light alloy due to the sliding contact with the belleville springs or the transmitting gear, to thereby prevent a reduction in preset load of the belleville springs due to the wear.
In order to effectively prevent the wear of the clutch housing by the thrust washer, it is necessary to mount the thrust washer relatively non-rotatably to the clutch housing. For this purpose, the prior art clutch employs a structure in which detent bores are provided in the thrust washer, and detent projections are formed on an outer surface of the clutch housing so that detent bores are fitted into the detent bores, as disclosed in Japanese Patent No. 3120291.
However, the above conventional structure has the following disadvantages: A sufficient fitting depth between the detent projections and the detent bores cannot be ensured because of a relatively small thickness of the thrust washer, and if the thrust washer is floated even slightly from the outer surface of the end wall of the clutch housing during an assembling process, the fitting between the detent projections and the detent bores is released, resulting in a poor assemblability; and if the thickness of the thrust washer is increased to increase the fitting depth between the detent projections and the detent bores in order to overcome the above disadvantage, the axial dimension of the clutch is increased by a value corresponding to an increment in thickness of the thrust washer, thereby bringing about a problem deteriorating to some extent the compactness of the clutch.
The present invention has been accomplished with the above circumstances in view, and it is an object of the present invention to provide a clutch which employs a thrust washer having a smaller thickness, and can prevent the relative rotation of the clutch housing and the thrust washer relative to each other, while providing a good assemblability.
To achieve the above object, according to a first feature of the present invention, there is provided a clutch comprising: a bottomed cylindrical clutch housing made of a light alloy and having an end wall; a retainer plate secured to the end wall with a given distance left therebetween; an iron transmitting gear disposed between and connected to the end wall and the retainer plate, for rotation relative to the end wall and the retainer plate in a predetermined range of angle; damper springs interposed between the transmitting gear and the clutch housing as well as the retainer plate, for moderating a torque shock generated between them; belleville springs interposed between the transmitting gear and the clutch housing as well as the retainer plate, for urging the transmitting gear toward one of the clutch housing and the retainer plate; and a thrust washer mounted to an outer face of the end wall of the clutch housing, for preventing contact between the end wall and the belleville springs as well as the transmitting gear; wherein a detent bore is provided in the end wall of the clutch housing, and a detent claw is formed on the thrust washer so that the detent claw is engaged into the detent bore.
The transmitting gear corresponds to a driven gear 2 in the below-described embodiment of the present invention.
With the first feature, in mounting the thrust washer to the clutch housing, the detent claws formed by bending the thrust washer are brought into engagement with the detent bores in the end wall. Therefore, even if the thrust washer is formed to have a small thickness, a sufficient depth for engagement between the detent claws and the detent bores can be ensured and hence, even if the thrust washer is floated even slightly from the outer surface of the end wall of the clutch housing to some extent during an assembling process, the detent claws can be prevented from being disengaged from the detent bores, leading to an improvement in assemblability of the clutch. Moreover, it is possible to provide a reduction in axial dimension of the clutch by the employment of the thinner thrust washer.
According to a second feature of the present invention, in addition to the first feature, the length of the detent claws on the thrust washer is set at a value equal to or larger than 1.5 times the thickness of the thrust washer.
With the second feature, it is possible to ensure a good bending formability of the detent claws by pressing.
According to a third feature of the present invention, in addition to the second feature, the length of the detent claws on the thrust washer is set longer than the length of the detent bores.
With the third feature, it is possible to ensure a good formability of the detent claws and to prevent slipping-off of the detent claws from the detent bores further reliably during assembling of the clutch.
According to a fourth feature of the present invention, in addition to any of the first to third features, a lubricating oil is supplied from the inside of the clutch housing through the detent bores toward the damper springs.
With the fourth feature, the detent bores also serves as oil supply bores and hence, it is possible to provide an improvement in durability of the portions of the damper springs and components around the damper springs, and to simplify the structure.